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Particularly Low Permeability Reservoir Characteristics & Comprehensive Evaluation Of Chang3 Reservoir In Huachi Area, Ordos Basin

Posted on:2011-07-14Degree:MasterType:Thesis
Country:ChinaCandidate:J W MoFull Text:PDF
GTID:2120360305959304Subject:Mineralogy, petrology, ore deposits
Abstract/Summary:PDF Full Text Request
Basing on detailed description and observation of drilling cores, and various analytical and measurement methods including identification and quantitative statistics of thin sections, electron scan microscope, high pressure mercury intrusion, relative permeability experiments, the petrology, reservoir properties, micro-pore structure and percolation mechanism is studied in Chang3 reservoir of Huachi Area, Ordos Basin to find the affecting factors of particularly low permeability reservoirs on the basis of scrutiny in structure and microfacies. The main conclusions run as follow:(1)The depositional system in study area belongs to braided-meandering river delta front deposit. The microfacies developments of underwater distributary channel, mouth bar, distributary bay and front sheet sand facies. The sediment's composition, structure is relatively higher in distributary channel and mouth bar facies. Because of differential compaction, many small nose structures were formed which are small in scale but greatly influence the distribution of reservoirs in the study area.(2)Lithic feldspathic sandstone is the main type of sandstone in study Area, which sorting is relatively good, rounded degree is times angular. The main form of cementation is Pore-Film and Pore-Increasing. Detrital quartz are the main ingredients, followed by feldspar and debris, which are mainly cemented by hydrosialite and carbonatite.(3)Pore types are mainly residual intergranular pores, followed by feldspar dissolution porosity and a small amount of debris dissolution pore and occasionally intercrystals pore. And the main types of pore throat are flake throats, followed by necking-shaped throats and bundle-like throats.(4)According to the results of mercury intrusion, capillary pressure curve can be divided into good, medium and poor in three types. There are bimodal distributions which are in favor of rough throat, single peak forms which are in favor of rough throat or thin throat in Chang3 Reservoir. All these factors make the sorting coefficient becomes larger, the mean coefficient becomes smaller, the coefficient of variation changes greatly, the pore-throat contrast is big. Then makes the pore volume smaller, sorting of throats worse and the connected space in Chang3 Reservoir is small.(5)The reservoir characteristics of Chang3 Reservoir in Huachi Area are affected by sedimentation, structure and diagenesis. Favorable reservoirs, which formed small nose structures were generated in underwater distributary channel or mouth bar, and formed relatively good combination of reservoir and cap rock. Organic fluids flowed in the residual intergranular pores which were protected by chlorite formed in the earlier period and dissolved feldspar or lithic grains. As a result, Intergranular pore-dissolved pores become good reservoir storage space and migration channel for oil and gas.(6)Basing on the rock characteristics, the porosity and permeability characteristics, the micro-pore structure and the influence factors of reservoir, Chang3 reservoir sandstones are divided intoⅠ,Ⅱ,ⅢandⅣclass in Huachi Area, in which I Reservoirs are good reservoirs, II Reservoirs are medium reservoirs, III Reservoirs are poor reservoirs, andⅣReservoirs are non-reservoir. And basing on this classification, the Favorable reservoir zones have been predicted under the combination of drilling, logging and results of oil production test. And oil-bearing areas were calculated to 534.95 km2 in 39 favorable delineated Well. Petroleum geological reserves were calculated to 9586.41×104t in Seven reservoirs favorable block at last in Huachi Area.
Keywords/Search Tags:Huachi Area, Micro-pore structure, high pressure mercury intrusion, reservoir Characteristics, reservoir Evaluation, integrated Forecast
PDF Full Text Request
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